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In this section, you will learn about LabVIEW debugging techniques.

If a VI does not run, it is a broken, or nonexecutable, VI. The Run button often appears broken, shown at left, when you create or edit a VI. If it is still broken when youfinish wiring the block diagram, the VI is broken and will not run. Generally, this means that a required input is not wired,or a wire is broken.

Finding errors

Click the broken Run button or select Windows>>Show Error List to display the Error list window, which lists all the errors. Double-click an error description to display therelevant block diagram or front panel and highlight the object that contains the error.

Execution highlighting

View an animation of the execution of the block diagram byclicking the Highlight Execution button, shown in . Execution highlighting shows the flow of data on the block diagram from one node to anotherusing bubbles that move along the wires. Use execution highlighting in conjunction with single-stepping to see howdata move from node to node through a VI.

Execution highlighting greatly reduces the speed at which the VI runs.

Single-stepping

Single-step through a VI to view each action of the VI on the block diagram as the VI runs. The single-steppingbuttons affect execution only in a VI or subVI in single-step mode. Enter single-step mode by clicking the Step Over or Step Into button. Move the cursor over the Step Over , Step Into , or Step Out button to view a tip strip that describes the next step if you clickthat button. You can single-step through subVIs or run them normally.

If you single-step through a VI with execution highlighting on, anexecution glyph, shown in , appears on the icons of the subVIs that are currently running.

Probes

Use the Probe tool, shown in , to check intermediate values on a wire as a VFI runs. Whenexecution pauses at a node because of single-stepping or a breakpoint, you also can probe the wire that just executedto see the value that flowed through that wire.

You also can create a custom probe to specify which indicator you use to view the probed data. For example, ifyou are viewing numeric data, you can choose to see that data in a chart within the probe. To create a custom probe,right-click a wire and select Custom Probe>>New from the shortcut menu.

Breakpoints

Use the Breakpoint tool, shown in , to place a breakpoint on a VI, node, or wire on the block diagram and pause execution at thatlocatiFon. When you set a breakpoint on a wire, execution pauses after data pass through the wire. Place a breakpointon the block diagram workspace to pause execution after all nodes on the block diagram execute. When a VI pauses at abreakpoint, LabVIEW brings the block diagram to the front and uses a marquee to highlight the node or wire thatcontains the breakpoint. LabVIEW highlights breakpoints with red borders for nodes and block diagrams and red bullets forwires. When you move the cursor over an existing breakpoint, the black area of the Breakpoint tool cursor appears white. Use the Breakpoint tool to click an existing breakpoint to remove it.

Questions & Answers

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linda Reply
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Shanjida
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
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Damian Reply
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Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
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Porter
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Yasmin
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Cesar
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Uday
what is nanomaterials​ and their applications of sensors.
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what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
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Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Labview graphical programming. OpenStax CNX. Apr 09, 2015 Download for free at https://legacy.cnx.org/content/col11408/1.2
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